Preparation of oil-dispersible highly basic sulfonates



PREPARATION OF OIL-DISPERSIBLE HIGHLY BASIC SULFONATES Oscar L. Wright, Ponca City, Okla., assignor to Continental Oil Company, Ponca City, Okla., a corporation of Delaware No Drawing. Application June 27, 1955 Serial No. 518,371

9 Claims. (Cl. 260-505) This invention relates to stable oil-dispersible highly basic metal-containing organic compositions and methods of preparing the same. Such compounds possessing increased reserve basicity find especial utility as additives in lubricating oils and likewise are useful for producng corrosion inhibiting compositions and similar purposes.

As is well known to those familiar with the art, mineral oils generally possess one or more undesirable characteristics. One such characteristic is their instability under operating conditions normally encountered in present day engines, such that within a relatively short time metal engine parts become contaminated with sludge, lacquer, and resinous materials. In most instances these contaminants are dispersed on and about piston rings causing them to stick. Another undesirablev characteristic of mineral oils is their tendency to oxidize producing acidic materials. These acidic materials corrode metal engne parts, particularly alloy bearings such as those of the cadmium-silver, copper-lead, etc., type. To overcome the detrimental effects of the oil instability, detergent type additives may be incorporated in the oil. At least two requirements must be met by heavy duty detergent type lubricating oil compositions for use in diesel and like internal combustion engines if a high degree of engine cleanliness is to be maintained. First the oil must possess power to disperse insolubles formed by fuel combustion or oil oxidation or both and, second, the oil must be capable of inhibiting acidic lacquer precursors which tend to be formed by either oil oxidation or interaction of the oil with sulfur acids produced from fuel combustion or both of these conditions. Compositions generally employed in oils for engine operation with high sulfur fuel (e.g. conventional metal sulfonates or phenates) are only mildly alkaline and their basicity is rapidly depleted during engine operation.

It is accordingly a principal object of this invention to provide metal-containing oil-dispersible organic compounds and a process for production of such dispersions.

It is another object of my invention to provide highly useful mineral oil compositions utilizing such dispersions.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends the invention then consists of the means hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain approved combinations of ingredients embodying my invention, such disclosed means constituting, however, but one of various forms in which the principle of the invention may be used.

Broadly stated, the highly basic sulfonate may be formed by first forming an alkaryl sulfonamide by reacting an alkaryl sulfonic acid with an excess of ammonium hydroxide which reaction is carried out at an elevated temperature. Upon completion of the reaction between the sulfonic acid and the ammonium hydroxide the product is heated to a temperature within the range of about 180 to 220 or even higher in order to decompose any ammonium sulfonate formed during the reaction. The

hired States Patent alkaryl sulfonamide so produced is then diluted with an organic solvent and slowly added with agitation to an: alkaline earth metal oxide or hydroxide dissolved in a. polar solvent. During the addition of the sulfonamide to the solution of the alkaline earth metal compound the temperature is maintained at about 100 C. At the end of this reaction the solvents are removed by distillation leaving as a residue a highly basic product which is bright and easily dispersed in lubricating oil. Alternatively the product may be blown with carbon dioxide either during the addition of the sulfonamide solution to the solution containing the alkaline earth metal compound or at the completion thereof after which the solvents are removed.

Before proceeding with specific examples illustrating my invention it may be well to indicate in general the nature of the materials required in the process.

The final alkaryl sulfonate must be oil-dispersible and as a consequence any sulfonic acid is suitable which will produce an oil-dispersible sulfonate.

Typical alkaryl hydrocarbons which may be used are those obtained by the reaction of excess of benzene, toluene, xylene or similar hydrocarbon with an alkylating agent in the presence of a Friedel-Crafts type catalyst. The alkylating agent may be a 9 to 18 carbon straight or branched chain olefin, alcohol, or halide. Preferred alkylating agents are the 9 to 18 carbon polymers of propylene such as tripropylene, tetrapropylene, pentapropylene, hexapropylene, or mixtures thereof. Other alkylating agents that may be used include nonyl, decyl, dodecyl, octadecyl alcohols and chlorides. A suitable alkaryl hydrocarbon which is also available commercially in large quantities is a blend of monoalkylbenzenes sometimes called dodecylbenzene. This particular product is obtainable from Continental Oil Company under the trade name Neolene 400. Typical physical properties of dodecylbenzene or Neolene 400 are as follows:

Specific gravity at 16 C. 0.8742 Average molecular weight 232 A.S.T.M. .D-158 Engler:

I.B.P. 535 F. 5 545 F. 10 550 F. 50 560 F. 580 F. 97 592 F. F.B.P. 603 F. Refractive index at 20 C. 1.4885 Viscosity at 20 C. 14 centipoise Bromine number 0.16

Another suitable alkaryl hydrocarbon is the detergent alkylate sometimes called polydodecylbenzene. Its typical physical properties are as follows:

. Pour point -25 F.

The alkaryl hydrocarbons may be sulfonated by any of the methods well known to those skilled in the art to produce the corresponding sulfonic acid using such sulfonating agents as sulfuric acid, oleum, sulfur trioxide, chlorosul fonic acid etc.

Other sulfonic acids that may be used in the preparation of the highly basic sulfonates of my invention are those prepared by treating petroleum oils of the lubricating oil range with strong sulfuric acid and are commonly known as mahogany acids. Specifically a petroleum oil distillate having a Saybolt Universal viscosity at 100 F. of from about 200 seconds to about 850 seconds is treated with from about 6 to about 9 pounds of fuming sulfuric acid per gallon of oil in one-half pound increments to produce the mahogany acids.

Any organic solvent may be used for diluting the sulfonic acid-ammonium hydroxide reaction product provided it meets .the following criteria:

(1) Is a solvent for the reaction product, (2) Forms an azeotrope with water, and

(3) Has a boiling point preferably below about 200 C.

Specific examples of suitable solvents include naphtha and the aromatic hydrocarbons such as benzene and its homologues; i.e., toluene, xylene, mesitylene, and ethyl benzene. For economical reasons I prefer to use benzene or naphtha.

Polar solvents which may be used for dissolving the alkaline earth metal compound include water, alcohol, particularly saturated aliphatic alcohols containing not more than 4 carbon atoms, solutions of water and alcohol, ammonium hydroxide, and amines such as alkylamines and alkanolamines.

Either water or an alcohol may be used for dissolving barium hydroxide or oxide, however, an alcohol is preferred because when an alcohol is used as the solvent a final product having a base number in excess of 100 is obtained. When water is used as the solvent the base number of the final product is always less than 100; generally not greater than about 55.

When calcium and magnesium compounds are used, ammonium hydroxide or an amine is preferred as the specified in the appended claims. Parts given are parts by weight.

Example 1 A polydodecylbenzenesulfonamide was prepared by adding 2310 parts of a 2:1 70 naphtha solution of polydodecylbenzenesulfonic acid (.72 meq./ gm.) and 200 parts of aqueous ammonium hydroxide to a reaction vessel. The contents were heated with stirring until all the solvent was removed. After the removal of the solvent the reaction mixture was heated to 220 'C. and maintained at that temperature for a period of two hours. 1080 parts of pale oil and 650 parts of benzene were then added to the mixture to form the stock solution for use in later examples. The pale oil used in this example, and the other examples, is a 170 SSU value at 100 F.

Example 2 A dodecylbenzenesulfonamide was prepared by adding 1000 parts of a 2:1 70 naphtha solution of dodecylbenzenesulfonic acid (1.02 meq./gm.) and 100 parts aqueous ammonium hydroxide to a reaction vessel. The contents were heated with stirring until all the solvent was removed. After the removal of the solvent the reaction mixture was heated to 220 C. and maintained at that temperature for a period of two hours. 350 parts of pale oil and 250 parts of benzene were then added to the mixture to form the stock solution for use in later examples.

Example 3 A solution of 20 parts (234 meq.) barium hydroxide in 100 parts of water was added to a reaction vessel and heated to 100 C. with agitation. When the temperature solvent because these compounds are much more soluble in such solvents than in water.

The materials are admixed in any suitable reaction vessel preferably fitted with means for agitation. Although agitation is essential, rapid agitation is not necessary for the formation of the highly basic sulfonates as such sulfonates may be produced with very slow mixing. The components of the composition alkaryl sulfonate plus the alkaline earth metal oxide or hydroxide dissolved in a suitable solvent may be combined in the presence of a hydrocarbon oil as a diluent. After thorough admixing the temperature is raised to the point at which the solvent is removed by distillation. If desired, the product may be centrifuged or filtered in order to produce a bright product but such after treatment is usually unnecessary.

All of the base numbers of the products of this invention were determined by the acetic acid titration method which utilizes glacial acetic acid as the solvent and a solution of perchloric acid in glacial acetic acid as the titrant. The method is especially adapted for determination of this type since equilibria are obtained rapidly. The procedures for carrying out acetic acid titrations are generally outlined in Analytical Chemistry, vol. 23, No. 2, February 1951, page 337, and vol. 24, No. 3, March 1952, page 519.

In order to disclose the nature of the present invention still more clearly, the following illustrative examples will be given. It is to be understood that the invention is not to be limited to the specific conditions or details set forth in these examples except insofar as such limitations are reached C., 100 parts of the sulfonamide stock solution prepared in Example 1 was slowly added to the reactor with agitation while the temperature was maintained at 97 C. During the addition of the sulfonamide, water and benzene were removed by evaporation. After all the sulfonamide had been added, 72 parts of benzene was added, the resulting solution filtered and finally the solvent removed. The product so obtained was very bright and had a base number of 55.

Example 4 The procedure of Example 3 was repeated with the exception that 18 parts (235 meq.) barium oxide in 100 parts of methyl alcohol was added to the reacting vessel rather than 20 parts of barium hydroxide in 100 parts of water. The product so obtained was very bright and had a base number of 114.

Example 5 A mixture of 100 parts of a 50% active solution of polydodecylbenzenesulfonamide in pale oil, 200 parts toluene, 50 parts methanol and 14 parts of calcium hydroxide was added to a reacting vessel. While the contents were stirred vigorously carbon dioxide was passed through the mixture for a period of 20 minutes. After the addition of the carbon dioxide the mixture was heated to remove the volatile solvents. The residue was taken up in benzene and filtered and finally the solvent was removed. The product so obtained was very bright and had a base number of 77.

Example 6 The procedure of Example 5 was repeated except 11 parts of magnesium hydroxide was substituted for the 14 parts of calcium hydroxide. The base number of the final product was 64.

Example 7 A solution consisting of 14 parts calcium hydroxide and 50 parts of ethanol amine was added to a reacting vessel and heated to 100 C. with agitation. When the temperature reached 100 C., 100 parts of a 35% active solution of dodecylbenzenesulfonamide in pale oil pre pared as described in Example 2 was slowly added to the reactor with agitation while the temperature was maintained at 97 C. After the addition of the sulfonamide, ethanolamine and benzene were removed by evaporation, 72 parts of benzene was added, and the resulting solution filtered and finally the solvent removed. The product so obtained was very bright and had a base number of 75.

It will thus be seen that the oil-dispersible highly basic alkaryl sulfonate is produced by a condensation reaction. As used herein, and in the appended claims, the term condensing has the same meaning as it does in colloidal chemistry, namely, the gathering together of minute particles (molecules or atoms) of a substance to form particles of colloidal dimensions. It the latter means is used the mixture is reacted with a precipitating agent to convert the alkali or alkaline earth metal compound to an oil-insoluble form, specifically a carbonate.

Lubricating compositions were prepared by adding 5 parts of the products of Examples 3 to 7 inclusive to 95 parts of a blend of SAE 30 lubricating oil containing a small amount of added sulfur as phosphorous pentasulfide treated wax olefin. The mixtures were then heated to about 140 F. with agitation to obtain a uniform blend.

The lubricating compositions thus produced together with the SAE 30 lubricating oil containing the phosphorous pentasulfide treated wax olefin as a control were subjected to cub engine tests. This test may be described briefly as follows: Four-cylinder cub gasoline engines (Internationals light tractor-engine adapted to a stand test) are run for 40 hours at 2500 rpm. with 11 brake horsepower output and oil temperature of 280 F. and a jacket temperature of 200 F. After completion of the run, the engines are disassembled and the parts thereof are inspected. During the same operation one run was made using the SAE 30 oil containing the phosphorous pentasulfide treated wax olefin as a control. The engines using the lubricating oil compositions containing the products of this invention as additives showed less wear than the engine using the control lubricant.

Although the finished product comprising the highly basic alkaryl sulfonate appears to be a true solution to the naked eye, a careful examination shows that the inorganic compound exists as a dispersoid in the surface active agent. When a dispersion is used it 'is necessary that the diameter of the dispersed inorganic compound be less than one micron to avoid any possibility of abrasion. When the dispersion is prepared in accordance to the method of my invention the diameter of the individual dispersed particles falls within this limit as can be demonstrated. For example, X-ray pictures indicate that the average diameter of the dispersed particles range from about 0.007 to somewhat less than 1 micron with a large portion of the particles ranging in size from about 0.01 to 0.2 micron in diameter.

It is apparent that many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof. The examples given are by way of illustration only and the invention is limited only by the terms of the appended claims.

I claim: 1. A method of preparing an oil-dispersible highly basic alkaryl sulfonate which comprises reacting an alkaryl sulfonic acid with a quantity of ammonium hydroxide in excess of that required for neutralization of said sulfonic acid, whereby a mixture of ammonium alkaryl sulfonate and an alkaryl sulfonamide is produced, heating said reaction mixture to a temperature within the range of 180-220 C. for a period of time sufiicient to decompose all the ammonium sulfonate present, diluting said product with an organic solvent which forms an azeotropic mixture with water, adding the resulting solution to an alkaline earth metal compound wherein the anion of said compound is selected from the group consisting of an oxide and a hydroxide dissolved in a polar solvent selected from the group consisting of ammonium hydroxide, saturated aliphatic alcohols containing up to 4 carbon atoms and ethanolamine at a temperature of about C., and then removing said solvent and any water present by evaporation to form the highly basic alkaryl sulfonate.

2. A method of preparing an oil-dispersible highly basic alkaryl sulfonate which comprises reacting an alkaryl sulfonic acid with a quantity of ammonium hydroxide in excess of that required for neutralization of said sulfonic acid, whereby a mixture of ammonium alkaryl sulfonate and an alkaryl sulfonamide is produced, heating said reaction mixture to a temperature within the range of ISO-220 C. for a period of time sufiicient to decompose all the ammonium sulfonate present, diluting said product with an organic solvent which forms an azeotropic mixture with water, adding the resulting solution to barium oxide dissolved in a polar solvent selected from the group consisting of ammonium hydroxide, saturated aliphatic alcohols containing up to 4 carbon atoms and ethanolamine at a temperature of about 100 C., and then removing said solvent and any water present by evaporation to form the highly basic alkaryl sulfonate.

3. The method of claim 1 wherein the alkaryl sulfonic acid is polydodecylbenzenesulfonic acid.

4. The method of claim 1 wherein the alkaryl sulfonic acid is dodecylbenzenesulfonic acid.

5. The method of claim 1 wherein the reaction mixture is blown with carbon dioxide before complete removal of solvent and any water present.

6. The method of claim 1 wherein the polar solvent is an aliphatic alcohol containing not more than 4 carbon atoms.

7. The method of claim 1 wherein the alkaline earth metal compound is calcium hydroxide.

8. The method of claim 1 wherein the alkaline earth metal compound is magnesium hydroxide.

9. The method of claim 1 wherein the polar solvent is ethanolamine.

References Cited in the file of this patent UNITED STATES PATENTS 2,480,638 Duncan et al. Aug. 30, 1949 2,671,757 Wisherd Mar. 9, 1954 2,695,910 Assefi et a1 Nov. 30, 1954 2,727,861 Brown et al Dec. 20, 1955 2,760,970 Le Suer Aug. 28, 1956 2,779,784 Sharrah Jan. 29, 1957 2,822,384 Gragson Feb. 4, 1958 

1. METHOD OF PREPARING AN OIL-DISPERSIBLE HIGHLY BASIC ALKARYL SULFONATE WHICH COMPRISES REACTING AN ALKARYL SULFONIC ACID WITH A QUANTITY OF AMMONIUM HYDROXIDE IN EXCESS OF THAT REQUIRED FOR NEUTRALIZATION OF SAID SULFONIC ACID, WHEREBY A MIXTURE OF AMMONIUM ALKARYL SULFONATE AND AN ALKARYL SULFONAMIDE IS PRODUCED, HEATING SAID REACTION MIXTURE TO A TEMPERATURE WITHIN THE RANGE OF 180-220*C. FOR A PERIOD OF TIME SUFFICIENT TO DECOMPOSE ALL THE AMMONIUM SULFONATE PRESENT, DILUTING SAID PRODUCT WITH AN ORGANIC SOLVENT WHICH FORMS AN AZEOTROPIC MIXTURE WITH WATER, ADDING THE RESULTING SOLUTION TO AN ALKALINE EARTH METAL COMPOUND WHEREIN THE ANION OF SAID COMPOUND IS SELECTED FROM THE GROUP CONSISTING OF AN OXIDE AND A HYDROXIDE DISSOLVED IN A POLAR SOLVENT SELECTED FROM THE GROUP CONSISTING OF AMMONIUM HYDROXIDE, SATURATED ALIPHATIC ALCHOLS CONTAINING UP TO 4 CARBON ATOMS AND ETHANOLAMINE AT A TEMPERATURE OF ABOUT 100*C., AND THEN REMOVING SAID SOLVENT AND ANY WATER PRESENT BY EVAPORATION TO FORM THE HIGHLY BASIC ALKARYL SULFONATE. 